*UPDATE: As of 6:20 it looks as though editing and missions are back online!*

As of the end of maintenance this afternoon, 1/21/2016, the Foundry has been taken offline for a yet to be determined length of time. Trendy posted the following in the official forums:

Hey folks!

With our update and everything coming up, we will once against temporarily be disabling UGC in STO in order to do Anniversary stuff and… other things. Also I have some Foundry stuff that I’m planning, but that’s me being a tease.

~Morrigan “LaughingTrendy”

So its possible we could be looking at downtime through the length of the anniversary event, so potentially a month, though this is all speculative at this point. It is worth noting the, and other stuff, so maybe we will have some goodies coming up?

and speaking of goodies, there was this in the patch notes for tribble on 1/20/2016: